Prior Art 1
A prior art of liquid crystal display device is disclosed, for example, in Japanese Unexamined Patent Publication No. 10-326515, in which a reflection type liquid crystal display element having a reflector is provided, and a front illumination device (front light) is disposed in front of the reflection type liquid crystal element, and this reflection type liquid crystal display device is used by turning off the front light where a sufficient quantity of ambient light is available, for example, in an outdoor place during daytime, and is used by lighting the front light where sufficient quantity of ambient light is not obtained.
Prior Art 2
Other prior art of liquid crystal display device is a semitransmission reflection type liquid crystal display device for making reflection type display using external light in a bright place, or transmission type display by backlight in a dark place.
As proposed, for example, in Japanese Unexamined Patent Publication No. Hei 10-186362, this semitransmission reflection liquid crystal display device has a liquid crystal display panel 100 including front side polarizing means, front side transparent plate, a transmission liquid crystal display unit, a back side transparent plate, and back side polarizing means, as shown in a sectional view of FIG. 19, in which a backlight 120 composed of a fluorescent lamp, a reflector and a triangular light-conducting plate is disposed at the opposite side (back side) of the observation side of this liquid crystal display panel 100, and semitransmission reflecting means 110 composed of half mirror or magic mirror having aluminum or the like affixed to a thin transparent film base by vapor deposition, with the film base being adhered, for example, to the back side of the back side polarizing means, is disposed between the backlight 120 and the transmission type liquid crystal display unit. In FIG. 19, reference numeral 130 denotes a light scattering plate comprising prism plate or diffusion film, 140 a circuit board for driving the liquid crystal display panel 100, and 150 a casing accommodating the liquid crystal display panel 100, semitransmission reflecting means 110, backlight 120, scattering plate 130 and circuit board 140.
In the semitransmission reflection type liquid crystal display device having such configuration, in a bright place, external light is taken in as indicated by arrow b, and reflection type display is made by making use of the light reflected by the semitransmission reflecting means 110, and in a dark place, the backlight 120 is lit, and transmission type display is made so that the display might be recognized by the light passing through the semitransmission reflecting means 110 as indicated by arrow a.
Prior Art 3
A different example of semitransmission reflection type liquid crystal display device is disclosed, for example, in Japanese Unexamined Patent Publication No. 2001-083494, that is, as shown in a sectional view of FIG. 20, this semitransmission reflection liquid crystal display device comprises a transparent first substrate 210; a transparent second substrate 220 disposed opposite to this first substrate 210, and having a color filter, a transparent electrode and an alignment film disposed at the side opposite to the first substrate 210; a liquid crystal 230 interposed between the first substrate 210 and second substrate 220; a backlight 240 disposed at the opposite side of the liquid crystal 230 of the first substrate 210; a transparent second insulation film 250 disposed at the side opposite to the second substrate 220 of the first substrate 210; a reflection electrode 260 disposed on the second insulation film 250 and having an opening for passing light from the backlight 240; a transparent first insulation film 270 disposed on the reflection electrode layer 260; and an alignment film 280 disposed on the first insulation film 270. In FIG. 20, moreover, reference numeral 291 denotes a polarizer, 292 a phase difference plate, and 293 a sealing material.
The semitransmission reflection type liquid crystal display device having such configuration can display by changing over between reflection type display using the light reflected by the reflection electrode 260 by taking in external light, and transmission type display using the light passing through the opening in the reflection electrode 260 emitted from the backlight 240. Further, in this prior art 3, unlike prior art 2, there is no transparent electrode between the reflecting means and the liquid crystal, and the optical path is shorter in the reflection type display, and therefore the parallax in display image is reduced and the brightness in display image is enhanced.
Prior Art 4
A conventional information appliance disclosed, for example, in Japanese Unexamined Patent Publication No. Hei 8-163638, is a mobile phone comprising, as shown in a perspective view of FIG. 21, a first main body having various operation switches, and a second main body having a liquid crystal display device connected thereto in an opening and closing manner for visibly displaying various kinds of information, and when the second main body is opened, a large screen image display is possible by the liquid crystal display device, and when the second main body is closed, it is reduced to a compact size suited to portable use. In FIG. 21, specifically, reference numeral 301 denotes the first main body having various function switches 307 including alphanumerical input switches, 302 denotes the second main body having the liquid crystal display device 304 for visibly displaying various kinds of information and coupled to the first main body 301 in an opening and closing manner, 303 denotes a coupling unit of the first main body 301 and second main body 302, 305 denotes an antenna, and 306 denotes a button switch for validating the inside and outside range display function when the second main body 302 is manipulated in closed state. Reference numeral 308 denotes a lamp displaying “inside” or “outside”, and specifically the inside range is displayed in a green light and the outside range in a red light, or the range is indicated by lighting or flickering, so that the inside and outside can be known at a glance.
In the information appliance having such configuration, when the button switch 306 is manipulated in the closed state of the second main body 302, the display lamp 308 displays, so that either “inside” or “outside” of the range can be visually recognized easily.
The conventional liquid crystal display device is thus constituted, and whether in reflection type liquid crystal display device or semitransmission reflection type liquid crystal display device, there is only one display panel, and there is even no idea about liquid crystal display device capable of displaying in both face and reverse sides.
In the conventional folding type information appliance, when the second main body is closed, although the inside or outside of the range can be visually recognized by the lit color, or lighting or flickering of the display lamp disposed separately from the liquid crystal display device, the display image by the liquid crystal display device cannot be recognized visually in the closed state of the second main body same as in the opened state. As a countermeasure, there might be considered to add an extra liquid crystal display device exclusive for closed state of the second main body, but the number of parts is increased, and hence the weight, volume and cost are increased.
Prior Art 5
Other conventional information appliance is an electronic appliance disclosed, for example, in Japanese Unexamined Patent Publication No. 2000-193956, which is one liquid crystal display device comprising, as shown in FIG. 22, a liquid crystal 516 enclosed by a pair of first reflection polarizer 599 and first absorption type polarizer 531, and second reflection polarizer 539 and second absorption type polarizer 519; and a light source light-conducting plate 512 disposed at the outermost side. In a bright place, reflection type image can be seen by making use of external light b from both sides, and in a dark place, by emitting light a from the light source light-conducting plate 512, a bright reflection screen can be observed through the light-conducting plate from the light source light-conducting plate 512 side, or from the opposite side, a bright transmission image can be seen.
Here, reference numeral 526 denotes a transparent electrode for driving the liquid crystal 516, and 550 a scattering layer.
However, in the liquid crystal display device disclosed in Japanese Unexamined Patent Publication No 2000-193956 and the electronic appliance using the same, when the surrounding is slightly bright, if the image is observed from the opposite side of the light source light-conducting plate 512, since the external light b is insufficient, the brightness is not enough even in the liquid crystal element driven by the transparent electrode 526 so that the external light b is reflected by the first reflection polarizer 599 to be displayed in white. At this time, to increase the brightness of the image, if the light source light-conducting plate 512 is lit to emit light a, the polarized light a after passing through the first reflection polarizer 599 and first absorption type polarizer 531 is reflected by the second reflection polarizer 539 in this liquid crystal element, and cannot pass, so that the brightness cannot be increased.
To the contrary, in the case of the liquid crystal display device being driven so that the external light b passes through the first reflection polarizer 599 and is not reflected to be displayed in black, the polarized light a passing through the first reflection polarizer 599 and first absorption type polarizer 531 is not reflected by the second reflection polarizer 539, but passes through the same, and hence the black display becomes bright and the contrast is lowered, thereby the display quality deteriorates.
The present invention is made to solve the problems of these prior arts, and it is a first object thereof to present a double-sided display type liquid crystal display device capable of displaying a bright image of excellent display quality on both face and reverse sides.
It is a second object thereof to present an information appliance allowing to recognize a display image by one liquid crystal display device in both opened state and closed state of a second main body, without adding a new image display device.